Apparatus for and improvement in carrying out chemical processes at elevated temperatures



Patented Mar. 26, 1935 APPARATUS FOR- PATENT OFFICE AND IDIPROVEMENT INCARRYING OUT CHEMICAL PROCESSES AT ELEVATED TEMPERATURES Mathias Pier,Heidelberg, and Walter Dinkler,

Mannheim Germany, assignors to I. G. Farbenlndustrie Aktiengesellschaft,

Frankforton-the-Main, Germany No Drawing. Application July 17, 1931,Serial No. 551,577. In Germany July 24, 1930 9 Claims. (01.23-252)cially suitable are alloys containing titanium,

The present invention relates to apparatus for and improvements incarrying out chemical processes at elevated temperatures and in thepresence of hydrogen.

In chemical reactions in which free hydrogen is present, either asreacting component or by formation during the reaction, such as variouskinds of materials, especially in the improvement of coals of allvarieties, tars, mineral oils and the like, their distillation andconversion products and carbonaceous residues, at elevated temperaturessuch as cracking operations, especially in the presence ofadded'hydrogen or gases supplying hydrogen and under pressure, such asthe destructive hydrogenation or the puriiication from sulphur withhydrogen at such elevated temperatures and pressures that no substantialsplitting of the materials under treatment occurs, or in the synthesisof ammonia, it is very difllcult to find suitable constructionalmaterials which are physically and chemically sufliciently resistant,especially to hydrogen and, if present, to sulphur, at the temperaturesand pressures employed. Thus iron is decarbonized by hydrogen andbecomes brittle after use for a short period of time. In particular,iron walls which have to bear pressure are readily destroyed by theaction of hydrogen so that either the walls must be kept cold or theymust be constructed of highly alloyed steels. Furthermore, in many casesiron has an injurious effect on the course of the reaction,for exampleby causing side re- -'actions, such as abundant formation of hydrocarbongases, deposition of coke or formation of undesirable polymerizationproducts in destructive hydrogenation or cracking processes whichreactions have a detrimental effect on the economy of the process.Moreover, there are only a very few materials, and these are notsufliciently available to render their general application economical,which are in any degree stable to sulphur and sulphur compounds,especially hydrogen sulphide.

We have now found that titanium alloys which contain aluminium, copper,cobalt ornickel or several of these metals, and, if desired, iron inaddition to one or'more of the said metals, constitute materials whichare resistant'in every respect, so that at least some, but preferablyall those parts of the apparatus which come into contact with the hotmaterials in the said processes may be constructed of or coated with thesaid alloys. The titanium content of alloys which contain iron should befrom 0.1 to 15 per cent, preferably from 0.5 to per cent. Espealuminiumand iron. In these alloys the content of titanium may be up to per cent,preferably from 0.5 to 3 per cent; the content of aluminium may be up toper cent, preferably from 5 to 8 per cent. With iron-titanium alloyscontaining cobalt, nickel or copper the content of the latter metals ispreferably up to 2 per cent. In the case of titanium alloys free fromiron, the cobalt, nickel or copper may be present. In this case thecontent of titanium in the alloys preferably ranges from 1 to 10 percent. Even at high temperatures as for example from 300 to 500 C. andmore and at high pressures, such as are employed for example in thedestructive hydrogenation of carbonaceous materials, the said alloys areextremely stable to attack by carbon monoxide, hydrogen or the sulphurcompounds contained in the initial materials or set free therefromduring the reaction or added to the reaction products. The alloys,especially those which contain titanium, aluminium and iron, have thegreat advantage contrasted with the chromium alloys hitherto proposedthat even with from 2 to t per cent of titanium (which is as abundantlyavailable as chromium) the same resistance to attack by hydrogen andsulphur compounds is attained as is attained with to per cent ofchromium. Moreover there is a further metallurgical advantage in thepreparation of the alloys byreason of the known deoxidizing action oftitanium.

The physical and chemical properties of ,the-

corrosive alloys hitherto proposed, whereby the preparation and workingup of the alloys is rendered. more simple and economical. The carboncontent of the said alloys may be varied as required. Usually it variesbetween 0 per cent and 1.5 per cent. The higher the content of carbonthe more stable to hydrogen and sulphur but also the more brittle do thesaid alloys become. If it is desired to employ as free as possible fromcarbon an iron-titanium alloy containing one of the hereinbefore definedmetals it is advantageous to start with metals obtained electrolyticallyand from iron obtained from iron carbonyl. In many cases the preparationof the alloys is preferably carried out by fusion in vacuo or in aninert gas atmosphere or by sintering of the finely divided alloycomponents.

Suitable alloys are those for example having the composition: 1.5 percent of titanium, 5 per cent of aluminium and 93.5 per cent of iron; 2per cent of titanium, 6 per cent of aluminium, 2 per cent of silicon,1.5 per cent of manganese and 88.5 per cent of iron; 3 per cent oftitanium, 5 per cent of aluminium, 2 per cent of tungsten, 2 per cent ofcobalt and 88 per cent of iron; 2 per cent of titanium, 10 per cent ofaluminium and 88 per cent of iron.

The titanium alloys as hereinbefore defined have the further remarkableadvantage that they do not scale off when exposed to hot gases, inparticular to heating gases containing oxidizing constituents, such asoxygen or carbon dioxide. This fact is of great importance for theconstruction of the heat transferring devices, such as preheating tubes,which when constructed of the materials hitherto in use are very liableto scale off at the surfaces which come into contact with the heatinggases.

The employment of the said alloys is of considerable importance in thetreatment of coals, tars, mineral oils, their distillation andconversion products with hydrogen under pressure by destructivehydrogenation. Since the said alloys have the further practicaladvantage that the transfer of heat by these alloys is good, they areeminently suitable also for constructing preheaters and heatregenerators. The alloys have the further favorable property of causingpractically no deposition of carbon or formation of methane, such as isreadily the case for example with the usual iron alloys. They maytherefore be employed with advantage in the distillation or generallyfor the heat treatment of carbonaceous and sulphur containing substancesas for example for cracking or low temperature carbonization or in thegasification of solid or liquid carbonaceous substances and also forroasting substances containing sulphur, such as ores, or in theregeneration by heat-treatment of catalysts used in hydrogeneration orcracking processes, or when working with carbon monoxide, as for examplein the preparation of metal carbonyls. The alloys may also be usedadvantageously as the constructional or coating materials for apparatusfor other reactions in which hydrogen is employed under pressure, as forexample for the synthesis of ammonia or for the catalytic reduction ofthe oxides of carbon.

The following examples will further illustrate the nature of thisinvention but the invention is not restricted to these examples.

Example 1' Mexican Panuco oil containing 4.5 per cent of sulphur istreated with hydrogen under a pressure of 200 atmospheres at atemperature of 450 C. in the presence of a catalyst consisting of equalparts of molybdic acid and zinc oxide. The parts of the apparatus whichcome into contact with the hot treated materials and its vapors arelined with an alloy consisting of 1.5 per cent of titanium, 6 per centof aluminium and 92.5 per cent of iron. After use for about 3 monthsthere is no appreciable attack on the material of the apparatus.

Example 2 A mixture of '75 per cent of hydrogen and 25 per cent ofnitrogen is allowed to flow at from 500 to 550 C. under a. pressure of200 atmospheres over an iron catalyst activated with about 10 per centof aluminium and small amounts of potassium nitrate, in a high-pressurevessel which is lined with an alloy consisting of 1 per cent oftitanium, 5 per cent of aluminium, 3 per cent of chromium and 91 percent of iron. The eiiluent gases containing ammonia are led through aheat exchanger consisting of a bundle of tubes constructed of the saidalloy. Even after use for several months the alloy employed shows nosigns of attack.

What we claim is:

1. In chemical relations effected at elevated temperatures and in thepresence of hydrogen the step which comprises confining the reactants bya surface consisting of an alloy of titanium containing iron andaluminium, the content of titanium ranging from .1 to 15 per cent, thatof aluminium ranging from 5 to 15 per cent and the major portion of theremainder being iron.

2. In chemical reactions eflfected at elevated temperatures and in thepresence of hydrogen the step which comprises confining the reactants bya surface consisting of an alloy of titanium containing iron andaluminium, in which the content of titanium ranges between 0.5 and 5 percent, that of aluminium ranges between 5 and 8 per cent and the majorportion of the remainder 15 136011.

3. In chemical reactions effected at elevated temperatures and in thepresence of hydrogen the step which comprises confining the reactants.by a surface consisting of an alloy of titanium, iron and aluminium, thecontent of titanium ranging .from .1 to 10 per cent, that of aluminiumranging from 5 to 15 per cent and the remainder being iron.

4. In chemical reactions efiected at elevated temperatures and in thepresence of hydrogen the step which comprises confining the reactants bya surface consisting of an alloy of .1 to 15 per cent of titanium, 5-15per cent aluminium, up to 5 per cent of at least one 01 the elementschromium, tungsten, molybdenum, vanadium, silicon, manganese, tin, zinc,lead, silver and beryllium, the remainder being iron.

5. In the destructive hydogenation of a carbonaceous material the stepwhich comprises confining the reactants by a surface consisting of analloy of titanium, iron and aluminium, the content of titanium rangingfrom .1 to 15 per cent, that of aluminium ranging from 5 to 15 per centand the remainder being iron.

6. In the synthesis of ammonia the step which comprises confining thereactants by a surface consisting of an alloy of titanium, iron,aluminium and chromium, the content of titanium ranging from .1 to 15per cent, that of aluminium ranging from 5 to 15 per cent, that ofchromium ranging from 3 to 5 per cent and the remainder being IIOll.

7. In chemical reactions eflfected at .elevated temperatures and in thepresence of hydrogen the step which comprises confining the reactants bya surface consisting of an alloy of titanium, iron and aluminium inwhich the contents of titanium and of aluminium range between 0.1 and 10per cent and between 5 and 8 per cent respectively and the remainder isiron.

8. In chemical reactions effected at elevated temperatures and in thepresence of hydrogen the step which comprises confining the reactants bya surface consisting of an alloy of iron containing from 0.1 to 10 percent of titanium, from 5 to 8 per cent of aluminium and up to 5 per centof at least one of the elements chromium, tungsten, molybdenum,vanadium, silicon, manganese, tin,

5 zinc, lead, silver and beryllium the remainder being iron.

9. Apparatus for carrying out chemical reactions at elevatedtemperatures and in the presence of hydrogen, in which the innersurfaces of the walls exposed to the reacting materials are at least inpart composed of an alloy containing titanium, iron and aluminium, thetitanium content ranging from .1 to 10% and the aluminium contentranging from 5 to 15% of such alloy of titanium and the major portion ofthe remainder being iron.

MATHIAS PIER. WALTER DINIGJER.

